JP2016056444A - Aluminum alloy sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet excellent in designability, exhibiting a crystal grain pattern with large grain diameter on a sheet surface and capable of making contrast between grain particles clear.SOLUTION: The aluminum alloy sheet contains Mg:2.0 to 6.0 mass%, Mn+Cr:0.01 to 0.20 mass%, Fe:0.20 mass% or less, Si:0.10 mass% or less and the balance Al with inevitable impurities and has an average crystal grain diameter on a sheet surface of 1 to 10 mm and Cube orientation distribution density of the sheet surface of 20 or less to a random direction.SELECTED DRAWING: None

Description

  The present invention relates to an aluminum alloy plate, and more particularly, to an aluminum alloy plate excellent in design.

  Aluminum alloy plates used in a wide variety of industrial fields have been intensively studied on mechanical properties such as tensile strength, proof stress, elongation, and bending workability in order to satisfy the quality required by the target product.

The mechanical properties of aluminum alloy sheets are extremely important because they affect the quality of the product. However, the mechanical properties are not inferior to the mechanical properties, and the design properties that influence the user's desire to purchase are also important matters. It is recognized that there is.
Therefore, the following techniques have been proposed for improving the design of the aluminum alloy plate.

  For example, in Patent Document 1, Si: 0.05 to 0.15 wt%, Fe: 0.13 to 0.35 wt%, Mg: 2.0 to 5.0 wt%, Mn + Cr: 0.15 to 0.80 wt %, Further, Ti: 0.005 to 0.15 wt%, or Ti: 0.005 to 0.15 wt% and B: 0.0005 to 0.05 wt%, and the balance is Al and other impurities. There has been proposed an aluminum alloy material for expressing a crystal grain structure pattern.

JP 2005-325420 A

The technology according to Patent Document 1 is a technology for expressing a crystal grain pattern with a large grain size on the plate surface, but 1 to 6% (preferably 2 to 4) in order to prevent the crystal grains from becoming finer. %) Can only be cold rolled (specifically, cold rolling after annealing) at a very low reduction rate.
As a result, the technique according to Patent Document 1 has a small contrast between crystal grains appearing on the plate surface, and it cannot be said that the design is excellent.

  Therefore, the aluminum alloy plate according to the present invention is an aluminum alloy excellent in design that can express a crystal grain pattern with a large grain size on the plate surface and can make the contrast between crystal grains clear. It is an object to provide a board.

  That is, the aluminum alloy plate according to the present invention has Mg: 2.0 to 6.0 mass%, Mn + Cr: 0.01 to 0.20 mass%, Fe: 0.20 mass% or less, and Si: 0.10 mass. %, And the balance is Al and inevitable impurities, the average crystal grain size on the plate surface is 1 to 10 mm, and the Cube orientation distribution density on the plate surface is 20 or less relative to the random orientation. Features.

According to this aluminum alloy plate, since the average crystal grain size is within a predetermined range, a crystal grain pattern having a large grain size of 1 mm or more can be expressed on the plate surface.
Moreover, according to this aluminum alloy sheet, since the content of Mn + Cr is within a predetermined range, it is possible to set a large rolling reduction ratio in cold rolling (specifically, cold rolling after annealing). The contrast between crystal grains can be clarified by cold rolling with a large rolling reduction.
In addition, according to this aluminum alloy plate, since the Cube orientation distribution density is 20 or less, the effect of clearing the contrast between crystal grains can be ensured.
In addition, since the prior art which concerns on patent document 1 was made into the essential requirement to perform the cold rolling of a very low reduction rate, the distortion by the said cold rolling was not stabilized, but it varied in quality between products. There was also a problem that would occur. However, according to this aluminum alloy sheet, it is possible to set a large reduction ratio of cold rolling, so it is possible to suppress variations in quality (particularly, variations in crystal grains in the sheet width direction) between products. As a result, defective products can be reduced and productivity (throughput) can be improved.

  In addition, according to this aluminum alloy sheet, since the content of Mn + Cr is in a predetermined range, it is possible to control the rolling reduction rate of the final pass in the hot rolling process while omitting the cold rolling process itself. An aluminum alloy plate having a large grain size crystallized pattern on the plate surface, a clear contrast between the crystal grains, and a thick plate thickness (for example, a plate thickness of 2 mm or more). You can also

  In the aluminum alloy plate according to the present invention, the total content of Mn and Cr is preferably 0.01 to 0.14% by mass.

  According to this aluminum alloy plate, by setting the total content of Mn and Cr within a predetermined range, an effect of expressing a crystal grain pattern with a large grain size on the plate surface, and between the crystal grain and the crystal grain, The effect of sharpening the contrast can be made more reliable.

  The aluminum alloy plate according to the present invention may further contain Zr, and the total content of Mn, Cr, and Zr may be 0.01 to 0.20 mass%.

According to this aluminum alloy sheet, when Zr is contained, since the content of Mn + Cr + Zr is within a predetermined range, it is possible to set a large reduction rate in cold rolling (specifically, cold rolling after annealing). As a result, the contrast between crystal grains can be clarified by cold rolling with a large rolling reduction.
Moreover, according to this aluminum alloy sheet, since the content of Mn + Cr + Zr is in a predetermined range, it is possible to control the reduction rate of the final pass in the hot rolling process while omitting the cold rolling process itself. An aluminum alloy plate having a large grain size crystallized pattern on the plate surface, a clear contrast between the crystal grains, and a thick plate thickness (for example, a plate thickness of 2 mm or more). You can also

  In the aluminum alloy plate according to the present invention, the total content of Mn, Cr, and Zr is preferably 0.01 to 0.14% by mass.

  According to this aluminum alloy plate, by making the total content of Mn, Cr, and Zr within a predetermined range, an effect that a crystal grain pattern with a large grain size is expressed on the plate surface, and The effect of sharpening the contrast between them can be made more reliable.

  The aluminum alloy plate according to the present invention may further contain Cu, and the content of Cu may be 0.60% by mass or less.

  According to this aluminum alloy plate, since the Cu content is within a predetermined range, the effect of causing a crystal grain pattern with a large grain size to appear on the plate surface and the contrast between the crystal grain and the crystal grain are clear. The effect of doing can be demonstrated.

  The aluminum alloy plate according to the present invention preferably has a tensile strength of 150 MPa or more.

  According to this aluminum alloy plate, since the tensile strength is 150 MPa or more, the strength required for the alloy plate can be ensured.

  The aluminum alloy plate according to the present invention may be obtained by subjecting the aluminum alloy plate to a surface treatment.

  The aluminum alloy plate according to the present invention may have a resin film formed on the surface of the aluminum alloy plate.

  The aluminum alloy plate according to the present invention has a large grain size because the content of each component is in a predetermined range, the average crystal grain size is in a predetermined range, and the Cube orientation distribution density is in a predetermined range. The design can be made excellent by expressing the pattern on the plate surface and by making the contrast between the crystal grains clear.

It is an image of the photograph which shows the surface state of the specimen 1 (average crystal grain diameter: 4 mm, Cube orientation distribution density: 8). It is an image of a photograph showing the surface state of sample material 11 (average crystal grain size: 1 mm, Cube orientation distribution density: 23).

  Hereinafter, the form for implementing the aluminum alloy plate which concerns on this invention is demonstrated in detail.

[Aluminum alloy plate]
The aluminum alloy plate according to the present invention contains Mg, Mn + Cr, Fe, and Si in a predetermined range, the balance is made of Al and inevitable impurities, the average crystal grain size on the plate surface is in the predetermined range, and Cube The azimuth is not more than a predetermined value. And the aluminum alloy plate which concerns on this invention may contain Zr so that the total content of Mn, Cr, and Zr may become a predetermined range, and also contains Cu of content of a predetermined range. It may be. In addition, the aluminum alloy plate according to the present invention preferably has a tensile strength of a predetermined value or more.

  Hereinafter, the reason why the respective alloy components, average crystal grain size, Cube orientation, and tensile strength of the aluminum alloy plate according to the present invention are numerically limited will be described.

(Mg: 2.0-6.0% by mass)
Mg has the effect of improving the strength by solid solution strengthening in an aluminum alloy. Further, when it coexists with Si, it forms an Mg—Si intermetallic compound and contributes to the strength improvement. A desired strength can be obtained by setting the Mg content to 2.0 mass% or more. On the other hand, if the Mg content exceeds 6.0% by mass, the number of crystal grain nuclei becomes too large, and the average crystal grain size of crystal grains appearing on the plate surface becomes small.
Therefore, the content of Mg is 2.0 to 6.0 mass%, preferably 3.0 mass% or more and 5.0 mass% or less.

(Mn + Cr: 0.01-0.20 mass%)
Mn and Cr are essential components for expressing a crystal grain pattern with a large grain size on the plate surface. By setting the total content of Mn and Cr to 0.01% by mass or more, Mn and Cr that pin the growth of crystal grains are removed by solid solution in the finish annealing, and the pinning is removed. Crystal grains can be grown (coarse) to a diameter. On the other hand, if the total content of Mn and Cr exceeds 0.20% by mass, the average crystal grain size of the crystal grains appearing on the plate surface becomes small.
Therefore, the content of Mn + Cr (the total content of Mn and Cr) is 0.01 to 0.20 mass%, preferably 0.14 mass% or less, and particularly preferably 0.05 mass%. % Or more and 0.11% by mass or less.

In addition, since Mn and Cr are components that play substantially the same role in the aluminum alloy plate according to the present invention, as long as the total content of Mn and Cr is within the above range, the inclusion of either Mn or Cr The amount may be 0.00% by weight.
However, in order to ensure the effect of expressing a crystal grain pattern with a large grain size on the plate surface, the Mn content is preferably 0.01 to 0.10% by mass, and the Cr content is 0.01 -0.10 mass% is preferable.

(Fe: 0.20 mass% or less)
Fe is mixed into the aluminum alloy as a metal impurity, and in the aluminum alloy, Al—Mn—Fe intermetallic compound and Al—Mn—Fe—Si intermetallic compound are mixed together with Mn and Si. Generate. Although Fe contributes to improvement in strength, when the Fe content exceeds 0.20 mass%, the number of crystal grains having these intermetallic compounds as nuclei becomes too large, and crystal grains appearing on the plate surface. The average crystal grain size becomes small.
Therefore, the Fe content is 0.20% by mass or less (including 0% by mass), and preferably 0.01% by mass or more and 0.15% by mass or less.

(Si: 0.10 mass% or less)
Si is mixed into the aluminum alloy as a metal base impurity, and has the effect of improving the strength by solid solution strengthening in the aluminum alloy. Further, when it coexists with Mg, it produces an Mg-Si intermetallic compound. It contributes to strength improvement. However, if the Si content exceeds 0.10% by mass, the number of crystal grains centered on these intermetallic compounds will increase, and the average crystal grain size of the crystal grains appearing on the plate surface will decrease. End up.
Accordingly, the Si content is 0.10% by mass or less (including 0% by mass), and preferably 0.005% by mass or more and 0.06% by mass or less.

(When further containing Zr, Mn + Cr + Zr: 0.01 to 0.20 mass%)
Zr, like Mn and Cr, is a component that exhibits the effect of developing a crystal grain pattern with a large grain size on the plate surface. When Zr is further contained, by making the total content of Mn, Cr, and Zr 0.01% by mass or more, Mn, Cr, and Zr that pin the growth of crystal grains are dissolved in the finish annealing. Thus, the pinning is removed, and the crystal grains can be grown (coarse) to a desired grain size. On the other hand, if the total content of Mn, Cr and Zr exceeds 0.20% by mass, the average crystal grain size of the crystal grains appearing on the plate surface is reduced.
Therefore, the content of Mn + Cr + Zr (the total content of Mn, Cr and Zr) is 0.01 to 0.20% by mass, preferably 0.14% by mass or less, and particularly preferably 0.8. It is 05 mass% or more and 0.11 mass% or less.

  In addition, since Mn, Cr, and Zr are components that play substantially the same role in the aluminum alloy plate according to the present invention, so long as the total content of Mn, Cr, and Zr is within the above range, Mn, Cr, and Zr 0.001 mass% may be sufficient as content of any 1 component or 2 components of these.

(When further containing Cu, Cu: 0.60 mass% or less)
When the Cu content exceeds 0.60 mass%, the number of crystal grain nuclei is excessively increased, and the average crystal grain size of the crystal grains appearing on the plate surface is reduced.
Therefore, when Cu is contained, the Cu content is 0.60% by mass or less, and preferably 0.50% by mass or less.

(Inevitable impurities)
As unavoidable impurities, Ti, V, Zn, Ni, Bi, Pb, and the like may be contained within a range that does not hinder the effects of the present invention. Specifically, each may be contained in a range of 0.05% by mass or less and a total of 0.20% by mass or less, preferably 0.01% by mass or less and a total of 0.10% by mass or less, respectively.
And about Ti, V, Zn, Ni, Bi, Pb etc., if not exceeding the above-mentioned predetermined content, it is not only the case where it is contained as an unavoidable impurity but also a case where it is actively added. However, the effect of the present invention is not disturbed.
For example, in the case of Ti, for the purpose of refining the ingot structure in the casting process, Ti can be added as a single substance or Ti-B. Does not interfere with the effect.
Further, Fe, Si, and Zr and Cu that are not essential components that define only the upper limit value described above may also be included as inevitable impurities.
Of course, the content of each element listed as an inevitable impurity may be 0% by mass.

(Average crystal grain size: 1 to 10 mm)
The aluminum alloy plate according to the present invention has an average crystal grain size on the plate surface of 1 to 10 mm.
When the average crystal grain size is as large as 1 mm or more, it can be recognized by humans that the aluminum alloy plate is excellent in design when applied to various uses described later. On the other hand, when the average crystal grain size exceeds 10 mm, the formability is lowered.
Therefore, the average crystal grain size is 1 to 10 mm, preferably 3 mm or more and 8 mm or less.

The average crystal grain size can be measured by the following method.
The surface of the aluminum alloy plate after finish annealing in the manufacturing method described later is etched with Tucker's solution (hydrochloric acid, nitric acid, hydrofluoric acid), washed with water, dried, and then visually observed using the intercept method in the rolling direction. Calculate the diameter value. In the measurement using the intercept method, for example, one measurement line length is set to 50 mm, and the total measurement line length may be set to 50 × 15 mm by observing a total of five fields per three fields. . When the crystal grain size is less than 1 mm, the crystal grain appears by Barker method, and after taking a picture with an optical microscope, the average crystal grain size may be calculated similarly by the intercept method.
The average crystal grain size is controlled by the content of each alloy component described above, and among the processes of the manufacturing method described later, in particular, the reduction ratio in the second cold rolling process (in the case of the first embodiment) or It can be controlled by the rolling reduction of the final pass of the hot rolling process (in the case of the second embodiment).

(Cube orientation distribution density: 20 or less)
In the aluminum alloy plate according to the present invention, the Cube orientation distribution density on the plate surface is 20 or less with respect to the random orientation (specifically, the Cube orientation distribution density on the plate surface by the crystal orientation distribution function analysis is 20 with respect to the random orientation). The following). When the Cube orientation distribution density is 20 or less, the contrast between crystal grains can be made clear.
Therefore, the Cube orientation distribution density is 20 or less, and preferably 15 or less.

Cube orientation distribution density can be measured by the following method.
For example, the surface of the aluminum alloy plate after finish annealing in the manufacturing method described later (specifically, after finish annealing, buffed, then chemically polished with 10% hydrofluoric acid for about 30 seconds, washed and dried), for example, Cube orientation distribution density with respect to random orientation can be obtained by measuring using an X-ray diffractometer manufactured by Rigaku Corporation [model “Rigaku RAD-rX” (Ru-200B)]. Then, a crystal orientation distribution function analysis (ODF analysis) based on an incomplete pole figure may be performed using the X-ray diffraction apparatus. In detail, the incomplete pole figure of {100} plane and {111} plane is created by schluz reflection method, ODF analysis is performed by applying Bunge's iterative series expansion method (positivity method), and Cube orientation Distribution density can be determined.
The Cube orientation distribution density is controlled by the content of each of the above-described alloy components (particularly Mn + Cr, Mn + Cr + Zr), and among the steps of the manufacturing method described later, the reduction ratio (first first) in the second cold rolling step is particularly important. In the case of the embodiment) and the rolling reduction in the final pass of the hot rolling process (in the case of the second embodiment) can be controlled.

(Tensile strength: 150 MPa or more)
The aluminum alloy plate according to the present invention preferably has a tensile strength of 150 MPa or more. When the tensile strength is 150 MPa or more, the strength as an alloy plate for various uses described later can be ensured.
Accordingly, the tensile strength is preferably 150 MPa or more, and particularly preferably 200 MPa or more.

The tensile strength can be measured by the following method.
By cutting out a JIS No. 5 test piece from the aluminum alloy sheet after finish annealing in the production method described later so that the tensile direction is perpendicular to the rolling direction, and carrying out a tensile test in accordance with JIS Z2241: 2011, tensile strength Measure.
In addition, about tensile strength, while controlling by content of each above-mentioned alloy component, it can control especially by the heat history and rolling reduction of each process also in the process of the manufacturing method mentioned later.

(State of aluminum alloy plate)
The aluminum alloy plate according to the present invention basically refers to an alloy plate that has been subjected to finish annealing in the manufacturing method described below and before being subjected to surface treatment. Including those with surface treatment.
Here, “surface-treated” means that the pre-annealed alloy plate is pre-treated (sandblast, mechanical pre-treatment such as polishing, chemical pre-treatment such as degreasing, etching, etc.) A surface treatment that is generally performed, such as an anodizing treatment, a coloring treatment, or a sealing treatment.

However, in the case where the surface treatment is performed on the aluminum alloy plate, when etching is performed using an acidic chemical solution and then anodizing treatment (alumite treatment) is performed, irregularities are formed on the surface of the aluminum alloy plate. The reflectance decreases due to the unevenness. As a result, the surface of the aluminum alloy plate may appear dark, which may reduce design properties.
Therefore, when it is desired to improve the scratch resistance of the aluminum alloy plate by performing a surface treatment, the above-mentioned “surface-treated” is after etching using an acidic chemical solution. Instead of anodizing, those subjected to a treatment for forming a resin film are preferable.
The resin film is, for example, a fluorine resin film (specifically, see Japanese Patent No. 3966520, Japanese Patent No. 3846807, Japanese Patent No. 5255612, etc.) or a polyester resin film (specifically, a patent No. 4448511 etc.) or an epoxy resin film (specifically, see Japanese Patent No. 413427 etc.). And this resin film is not specifically limited about a film thickness, For example, what is necessary is just 0.1-10 micrometers.

(Use)
Since the aluminum alloy plate according to the present invention exhibits excellent design properties, the aluminum alloy plate can be applied to any tangible object that is required to have design properties, that is, humans can visually recognize.
For example, “for building materials” such as roofs, walls, floors, “for housings” for storing machinery and electrical equipment, “for outer panels or inner panels” for transportation equipment such as automobiles, ships, and railway vehicles, Alternatively, the aluminum alloy plate according to the present invention can be applied as “for beverage cans”.

  The thickness of the aluminum alloy plate according to the present invention is not particularly limited, and even if it is a thin plate thickness (for example, a plate thickness of less than 2 mm), it is a thick plate thickness (for example, a plate thickness of 2 mm or more). It may be selected appropriately according to the application.

  The aluminum alloy plate according to the present invention is as described above, but the other characteristics that are not clearly specified are not particularly limited as long as they are conventionally known and exhibit the effects obtained by the characteristics. Needless to say.

[Method for producing aluminum alloy sheet]
Next, the manufacturing method of the aluminum alloy plate concerning this invention is demonstrated.
Since the aluminum alloy plate according to the present invention can be manufactured by two methods, in the following, the method for manufacturing the aluminum alloy plate according to the first embodiment and the method for manufacturing the aluminum alloy plate according to the second embodiment, This will be explained separately.

(Method for producing an aluminum alloy plate according to the first embodiment)
The aluminum alloy plate according to the present invention includes a casting process, a homogenization heat treatment process, a hot rolling process, a first cold rolling process, an intermediate annealing process, a second cold rolling process, and a finish annealing process. , Manufactured by performing.
Moreover, you may manufacture the aluminum alloy plate which concerns on this invention by performing a surface treatment process after a finishing annealing process.
Hereinafter, the respective steps will be mainly described.

(Casting process)
In the casting process, the aluminum alloy having the above-described composition is melted, cast by a known casting method such as a DC casting method, cooled to below the solidus temperature of the aluminum alloy, and a predetermined thickness (for example, 400 (About 600 mm).

(Homogenization heat treatment process)
In the homogenization heat treatment step, the homogenization heat treatment is performed at a predetermined temperature before rolling the ingot cast in the casting step. By subjecting the ingot to homogenization heat treatment, internal stress is removed, solute elements segregated at the time of casting are homogenized, and intermetallic compounds precipitated at the time of casting cooling and thereafter grow.
The heat treatment temperature in this homogenization heat treatment step is preferably 400 to 550 ° C. By making it 400 degreeC or more, the above-mentioned homogenization effect can be acquired. On the other hand, when the treatment temperature exceeds 550 ° C., the intermetallic compound that becomes the nucleus of the crystal grains decreases, and the size of the finally obtained crystal grains increases.
The heat treatment time is not particularly limited, and may be 1 to 24 hours.

In the homogenization heat treatment step, even after “homogeneous heat treatment” after the homogenization heat treatment, the hot rolling is performed without cooling. ) Even after “2 times soaking” in which hot rolling is carried out after reheating after chamfering and chamfering, after the homogenization heat treatment, it is cooled to the hot rolling start temperature and hot rolling “Two-stage soaking” may be performed.
Here, when performing “one-time soaking” and “two-stage soaking”, it is only necessary to chamfer before the homogenization heat treatment step.

(Hot rolling process)
In the hot rolling step, the homogenized ingot is hot rolled.
The rolling start temperature and the rolling end temperature in this hot rolling process are not particularly limited, and for example, the rolling start temperature may be 400 to 550 ° C. and the rolling end temperature may be 250 to 380 ° C.
And it can be set as the hot rolled sheet (hot coil) of desired plate | board thickness by performing the hot rolling which consists of a several path | pass.

(First cold rolling process)
In the first cold rolling step, the hot rolled plate is cold rolled at a recrystallization temperature or lower (for example, normal temperature).
The rolling reduction in the first cold rolling step is not particularly limited, and may be 0 to 80%.
Note that the reduction rate of 0% indicates a case where intermediate annealing is performed after hot rolling (when the first cold rolling is not performed).

(Intermediate annealing process)
In the intermediate annealing step, the rolled sheet after the first cold rolling step is annealed.
The annealing temperature and annealing time in this intermediate annealing step are not particularly limited, and may be, for example, 300 to 450 ° C. and 1 to 12 hours.

(Second cold rolling process)
In the second cold rolling step, the rolled sheet after the intermediate annealing is cold-rolled at a recrystallization temperature or lower (for example, normal temperature).
The rolling reduction in this second cold rolling step is preferably 30% or more. When the content of Mn + Cr and Mn + Cr + Zr in the aluminum alloy plate is within the predetermined range defined by the present invention, the grain size of the finally obtained crystal grains is increased to a desired value by setting the rolling reduction to 30% or more. In addition, the contrast between crystal grains can be made clear. And as the rolling reduction increases, the grain size of the finally obtained crystal grains gradually decreases.
That is, according to the aluminum alloy plate according to the present invention, the reduction ratio of the second cold rolling process can be set larger than that of the conventional technique according to Patent Document 1.

(Finish annealing process)
In the finish annealing step, the rolled plate after the second cold rolling step is annealed.
The annealing temperature in the finish annealing step is preferably 450 to 550 ° C. By setting the annealing temperature to 450 ° C. or higher, Mn and Cr (further Zr), which pinned the growth of crystal grains, are dissolved, and the crystal grains grow (coarse) at a stretch. The diameter can be increased to a desired value. On the other hand, if the annealing temperature exceeds 600 ° C., it will melt.
The annealing time is not particularly limited and may be 1 to 12 hours.

  When annealing in the finish annealing step is continuous annealing (CAL) in which heating and cooling are performed rapidly, crystal grains do not sufficiently grow (coarse), so batch annealing (box annealing) is preferable. In addition, what is necessary is just to use a conventionally well-known thing at the time of performing batch annealing.

(Surface treatment process)
In the surface treatment step, the surface treatment is performed on the rolled plate after the finish annealing step.
The surface treatment in the surface treatment process includes “pretreatment” (mechanical pretreatment such as sand blasting and polishing, chemical pretreatment such as degreasing and etching), “anodizing treatment”, “coloring treatment”, and “sealing treatment”. And the like, and surface treatments generally performed.

  For example, in the surface treatment step, the rolled plate after the finish annealing step is washed with an aqueous sodium hydroxide solution (60 ° C., 10%) for 1 minute, and then smut is removed with an aqueous nitric acid solution (10%) for 1 minute. Just do it. Of course, after the pretreatment of cleaning and smut removal, an anodizing treatment → coloring treatment → sealing treatment may be performed.

However, in the surface treatment process, if etching is performed using an acidic chemical solution and then anodization (alumite treatment) is performed, irregularities are formed on the surface of the aluminum alloy plate, and the reflectance decreases due to the irregularities. To do. As a result, the surface of the aluminum alloy plate may appear dark, which may reduce design properties.
Therefore, in the case of improving the scratch resistance of the aluminum alloy plate by surface treatment, when etching is performed using an acidic chemical solution, the resin film is not subjected to anodization after the etching. It is preferable to perform the process to form.
The treatment for forming the resin film includes, for example, formation of a fluorine-based resin film (specifically, see Japanese Patent No. 3966520, Japanese Patent No. 3846807, Japanese Patent No. 5255612, etc.), and formation of a polyester-based resin film. (Specifically, refer to Japanese Patent No. 4448511, etc.) and formation of an epoxy resin film (specifically, refer to Japanese Patent No. 41427, etc.).

Next, the manufacturing method of the aluminum alloy plate which concerns on 2nd Embodiment is demonstrated.
(Method for producing an aluminum alloy plate according to the second embodiment)
The aluminum alloy sheet according to the present invention is manufactured by performing a casting process, a homogenizing heat treatment process, a hot rolling process, and a finish annealing process.
Moreover, you may manufacture the aluminum alloy plate which concerns on this invention by performing a surface treatment process after a finishing annealing process.
Hereinafter, the respective steps will be mainly described.

(Casting process)
In the casting process, the aluminum alloy having the above-described composition is melted, cast by a known casting method such as a DC casting method, cooled to below the solidus temperature of the aluminum alloy, and a predetermined thickness (for example, 400 (About 600 mm).

(Homogenization heat treatment process)
In the homogenization heat treatment step, the homogenization heat treatment is performed at a predetermined temperature before rolling the ingot cast in the casting step. By subjecting the ingot to homogenization heat treatment, internal stress is removed, solute elements segregated at the time of casting are homogenized, and intermetallic compounds precipitated at the time of casting cooling and thereafter grow.
The heat treatment temperature in this homogenization heat treatment step is preferably 400 to 550 ° C. By making it 400 degreeC or more, the above-mentioned homogenization effect can be acquired. On the other hand, when the treatment temperature exceeds 550 ° C., the intermetallic compound that becomes the nucleus of the crystal grains decreases, and the size of the finally obtained crystal grains increases.
The heat treatment time is not particularly limited, and may be 1 to 24 hours.

In the homogenization heat treatment step, even after “homogeneous heat treatment” after the homogenization heat treatment, the hot rolling is performed without cooling. ) Even after “2 times soaking” in which hot rolling is carried out after reheating after chamfering and chamfering, after the homogenization heat treatment, it is cooled to the hot rolling start temperature and hot rolling “Two-stage soaking” may be performed.
Here, when performing “one-time soaking” and “two-stage soaking”, it is only necessary to chamfer before the homogenization heat treatment step.

(Hot rolling process)
In the hot rolling step, the homogenized ingot is hot rolled.
The rolling start temperature and the rolling end temperature in this hot rolling process are not particularly limited, and for example, the rolling start temperature may be 400 to 550 ° C. and the rolling end temperature may be 250 to 380 ° C.
And it can be set as the hot rolled sheet (hot coil) of desired plate | board thickness by performing the hot rolling which consists of a several path | pass.

Note that the rolling reduction of the final pass in the hot rolling step (specifically, the final pass rolling reduction of the finish hot rolling) is preferably more than 10% and 45% or less. When the content of Mn + Cr and Mn + Cr + Zr in the aluminum alloy sheet is within the predetermined range defined by the present invention, the grain size of the finally obtained crystal grains is set to a desired value by setting the rolling reduction ratio of the final pass within the above range. The value can be increased to a value, and the contrast between crystal grains can be made clear.
And, if the rolling reduction ratio of the final pass in the hot rolling process exceeds 45%, it becomes difficult to express a crystal grain pattern with a large grain size on the plate surface. It becomes impossible to obtain a rolled sheet.

(Finish annealing process)
In the finish annealing process, the rolled sheet after the hot rolling process is annealed.
The annealing temperature in the finish annealing step is preferably 450 to 550 ° C. By setting the annealing temperature to 450 ° C. or higher, Mn and Cr (further Zr), which pinned the growth of crystal grains, are dissolved, and the crystal grains grow (coarse) at a stretch. The diameter can be increased to a desired value. On the other hand, if the annealing temperature exceeds 600 ° C., it will melt.
The annealing time is not particularly limited and may be 1 to 12 hours.

  When annealing in the finish annealing step is continuous annealing (CAL) in which heating and cooling are performed rapidly, crystal grains do not sufficiently grow (coarse), so batch annealing (box annealing) is preferable. In addition, what is necessary is just to use a conventionally well-known thing at the time of performing batch annealing.

(Surface treatment process)
In the surface treatment step, the surface treatment is performed on the rolled plate after the finish annealing step.
The surface treatment in the surface treatment process includes “pretreatment” (mechanical pretreatment such as sand blasting and polishing, chemical pretreatment such as degreasing and etching), “anodizing treatment”, “coloring treatment”, and “sealing treatment”. And the like, and surface treatments generally performed.

  For example, in the surface treatment step, the rolled plate after the finish annealing step is washed with an aqueous sodium hydroxide solution (60 ° C., 10%) for 1 minute, and then smut is removed with an aqueous nitric acid solution (10%) for 1 minute. Just do it. Of course, after the pretreatment of cleaning and smut removal, an anodizing treatment → coloring treatment → sealing treatment may be performed.

However, in the surface treatment process, if etching is performed using an acidic chemical solution and then anodization (alumite treatment) is performed, irregularities are formed on the surface of the aluminum alloy plate, and the reflectance decreases due to the irregularities. To do. As a result, the surface of the aluminum alloy plate may appear dark, which may reduce design properties.
Therefore, in the case of improving the scratch resistance of the aluminum alloy plate by surface treatment, when etching is performed using an acidic chemical solution, the resin film is not subjected to anodization after the etching. It is preferable to perform the process to form.
The treatment for forming the resin film includes, for example, formation of a fluorine-based resin film (specifically, see Japanese Patent No. 3966520, Japanese Patent No. 3846807, Japanese Patent No. 5255612, etc.), and formation of a polyester-based resin film. (Specifically, refer to Japanese Patent No. 4448511, etc.) and formation of an epoxy resin film (specifically, refer to Japanese Patent No. 41427, etc.).

Up to this point, the method for producing an aluminum alloy plate has been described as being divided into two. However, when producing an aluminum alloy plate having a thin plate thickness (for example, a plate thickness of less than 2 mm), the aluminum alloy plate is produced according to the first embodiment. In the case of manufacturing an aluminum alloy plate having a thick plate thickness (for example, a plate thickness of 2 mm or more), it is preferable to manufacture the aluminum alloy plate according to the second embodiment.
Further, when an aluminum alloy plate having a Cube orientation distribution density of 15 or less and having a very sharp contrast between crystal grains is manufactured according to the first embodiment.

  The method for producing an aluminum alloy plate according to the present invention is as described above. However, in carrying out the present invention, other processes are performed between or before and after each process within a range that does not adversely affect each process. May be included. For example, after the finish annealing step and the surface treatment step, a cutting step for cutting the aluminum alloy plate into a predetermined size and a processing step for processing into a predetermined shape (bending, punching, etc.) may be included.

  In addition, as for conditions that are not clearly shown in the respective steps, it is sufficient to use conventionally known conditions, and it is needless to say that the conditions can be appropriately changed as long as the effects obtained by the processing in the respective steps are exhibited.

  Next, the aluminum alloy plate according to the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

[Production of test materials]
About the test materials 1-21 of Table 1, the aluminum alloy of the composition shown in Table 1 was melt | dissolved, the ingot was produced by semi-continuous casting, and the face-cutting process was performed, and it was set as thickness 580mm. This ingot is subjected to homogenization heat treatment, and then hot-rolled (starting temperature: 480 ° C., finishing temperature: 320 ° C., final plate thickness: 3 mm, final pass reduction ratio: shown in Table 1), A rolled sheet was used. Thereafter, first cold rolling (rolling rate: 58%), intermediate annealing (temperature: 350 ° C., time: 4 h), second cold rolling (rolling rate: shown in Table 1), finish annealing (temperature: 550 ° C.) , Time: 4h), the test material was produced.

  About the test materials 22-26 of Table 1, the aluminum alloy of the composition shown in Table 1 was melt | dissolved, the ingot was produced by semi-continuous casting, and it face-treated, and it was set as thickness 580mm. This ingot is subjected to homogenization heat treatment and then hot rolled (start temperature: 480 ° C., end temperature: 320 ° C., final plate thickness: shown in Table 1, final pass reduction ratio: shown in Table 1). Then, a hot rolled sheet was used, and finish annealing (temperature: 550 ° C., time: 4 h) was performed to prepare a test material.

  And to the test materials 1-26, the surface treatment was performed after finish annealing. In this surface treatment, the specimen is washed with an aqueous sodium hydroxide solution (60 ° C., 10%) for 1 minute, and then smut is removed with an aqueous nitric acid solution (10%) for 1 minute. there were.

[Evaluation]
(Average crystal grain size)
After etching the surface of the test material after removal of the smut with Tucker's solution (hydrochloric acid, nitric acid, hydrofluoric acid), washing with water and drying, visually determine the value of the average grain size using the intercept method in the rolling direction. Calculated. In the measurement using the section method, the length of one measurement line was 50 mm, and the total measurement line length was 50 × 15 mm by observing a total of five fields with three lines per field. When the crystal grain size was less than 1 mm, each crystal grain was revealed by the Barker method, and after taking a photograph with an optical microscope, the average crystal grain size was similarly calculated by the intercept method.

(Tensile strength)
A test piece of JIS No. 5 was cut out from the specimen so that the tensile direction was perpendicular to the rolling direction. Using this test piece, a tensile test was performed in accordance with JISZ2241: 2011, and the tensile strength was measured.
The crosshead speed was 5 mm / min, and the test was performed at a constant speed until the test piece broke.

(Cube orientation)
The Cube orientation was measured after finishing annealing, buffing, chemical polishing with 10% hydrofluoric acid for about 30 seconds, washing with water, and drying the surface of the test material. Cube orientation distribution density with respect to random orientation was determined by measurement using “Rigaku RAD-rX” (Ru-200B)]. ODF analysis was performed using an incomplete pole figure using the X-ray diffractometer. In detail, the incomplete pole figure of {100} plane and {111} plane is created by schluz reflection method, ODF analysis is performed by applying Bunge's iterative series expansion method (positivity method), and Cube orientation The distribution density was determined.

  Detailed aluminum alloy components and test results are shown in Table 1. In Table 1, those not satisfying the configuration of the present invention are indicated by underlining the numerical values.

[Examination of results]
About the test materials 1-10 and 22-24, since the requirements prescribed | regulated by this invention are satisfy | filled, while making the crystal grain pattern of a large particle size express on a plate surface, between a crystal grain and a crystal grain, The result was that the contrast could be sharpened.
Moreover, about the test materials 1-10, 22-24, also about tensile strength, it became 150 Mpa or more, and it was a result that it had also about the fixed intensity | strength requested | required of an alloy plate.
In addition, as shown in FIG. 1, the specimen 1 was confirmed to have a large average crystal grain size and excellent design properties.

On the other hand, the test material 11 had a Mg content that was less than the lower limit of the numerical range defined in the present invention, so that the tensile strength was low and the result was that it was unsuitable as an alloy plate. Moreover, since the content of Mg was less than the lower limit of the numerical range defined in the present invention, the specimen material 11 had a Cube orientation distribution density on the plate surface exceeding 20 relative to the random orientation.
In addition, as shown in FIG. 2, the sample material 11 was confirmed to have a small average crystal grain size and poor design properties.
In the test material 12, since the Mg content exceeded the upper limit of the numerical range defined in the present invention, the crystal grains expressed on the surface of the plate were small, resulting in poor design.
Since the total content of Mn and Cr exceeded the upper limit value of the numerical range defined in the present invention, the test material 13 had small crystal grains developed on the surface of the plate, resulting in poor design. It was.
Since the total content of the test material 14 and Mn and Cr exceeded the upper limit of the numerical range defined in the present invention, the crystal grains expressed on the plate surface were small, resulting in poor design. .

Since the Fe content of the test material 15 exceeded the upper limit of the numerical range defined in the present invention, the crystal grains expressed on the plate surface were small, resulting in poor design.
In the test material 16, since the Si content exceeded the upper limit of the numerical range defined in the present invention, the crystal grains expressed on the surface of the plate were small, resulting in poor design.
Since the total content of Mn, Cr and Zr exceeded the upper limit of the numerical range defined in the present invention, the test material 17 had a small crystal grain expressed on the plate surface, and the result that it was inferior in design. It became.
Since the total content of Mn, Cr, and Zr was less than the lower limit value of the numerical range defined in the present invention, the test material 18 had a small crystal grain expressed on the plate surface, and was inferior in design. It became.
In the test material 19, since the Cu content exceeded the upper limit of the numerical range defined in the present invention, the crystal grains expressed on the surface of the plate were small, resulting in poor design.
Since the test material 20 had a low rolling reduction in the second cold rolling and a small average crystal grain size, it was inferior in design.
The specimen 21 is based on the technique according to Patent Document 1, and the content of Mn + Cr exceeds the upper limit of the numerical range defined in the present invention, and the reduction ratio in the second cold rolling is low. For this reason, the Cube orientation distribution density on the plate surface exceeded 20 with respect to the random orientation. Therefore, the test material 21 had a low contrast between crystal grains appearing on the plate surface, and was inferior in design.
The test material 25 had a result that the total content of Mn, Cr, and Zr exceeded the upper limit of the numerical range defined in the present invention, so that the crystal grains expressed on the plate surface were small and the design properties were inferior. It became.
The test material 26 was inferior in design because the rolling reduction in the final pass in hot rolling was high and the average crystal grain size was small.

  From the above results, it was found that the aluminum alloy plate according to the present invention can develop a crystal grain pattern with a large grain size on the plate surface and can make the contrast between crystal grains clear.

In addition, about the test materials 1-10, 22-24, after forming the fluorine-type resin membrane | film | coat with a film thickness of 2 micrometers (formation by the method similar to Example 1 of the paragraph 0034 and 0040 of patent 3966520), Cube orientation distribution density was measured, and the result was almost the same as before formation.
Therefore, it was found that the resin film can enjoy the effects (such as wrinkle resistance) exhibited by the resin film without reducing the contrast between the crystal grains.

Claims (8)

Mg: 2.0-6.0 mass%, Mn + Cr: 0.01-0.20 mass%, Fe: 0.20 mass% or less, Si: 0.10 mass% or less, with the balance being Al and Inevitable impurities,
The average crystal grain size on the plate surface is 1-10 mm,
An aluminum alloy plate, wherein the Cube orientation distribution density on the plate surface is 20 or less with respect to the random orientation.   The total content of said Mn and said Cr is 0.01-0.14 mass%, The aluminum alloy plate of Claim 1 characterized by the above-mentioned. Further containing Zr;
2. The aluminum alloy plate according to claim 1, wherein a total content of the Mn, the Cr, and the Zr is 0.01 to 0.20 mass%.   The total content of said Mn, said Cr, and said Zr is 0.01-0.14 mass%, The aluminum alloy plate of Claim 3 characterized by the above-mentioned. Further containing Cu,
5. The aluminum alloy plate according to claim 1, wherein the Cu content is 0.60 mass% or less.   The aluminum alloy plate according to any one of claims 1 to 5, wherein the tensile strength is 150 MPa or more.   An aluminum alloy plate obtained by subjecting the aluminum alloy plate according to any one of claims 1 to 6 to surface treatment.   An aluminum alloy plate, wherein a resin film is formed on a surface of the aluminum alloy plate according to any one of claims 1 to 6.